Conventionally, a photocurable composition having high concealing property has been widely used in a coating material for a flexible wiring board (see Patent Literature 1), a casting material for a replica of a prototype model (see Patent Literature 2), a black stripe of lenticular lens (see Patent Literature 3), an adhesive agent for assembling an electronic equipment and the like (see Patent Literature 4), a sealing agent for a liquid crystal display (see Patent Literature 5), or the like. As a typical technique of imparting concealing property to a photocurable composition, mixing of carbon black of pigment can be mentioned. However, concealing property can be obtained, but most of active energy rays such as UV rays are absorbed into the carbon black, therefore, there has been a problem of causing poor curability when the concentration of the pigment is extremely high.
Under these circumstances, in Patent Literature 2, there is a disclosure of a photosensitive composition for casting, which contains a photoradical polymerization initiator, a leuco dye, a photoacid generator, and an ethylenically unsaturated compound, and the cured product has excellent photocurability while being black. This utilizes the fact that the generation speed of the “radical species generated by light irradiation” is faster than the generation speed of the “acid generated by light irradiation”. That is, the photosensitive resin composition is cured by the transmission of light to the extent of the deep portion before being blackened with an acid.